Anal stenosis is one of the complications after a hemorrhoidectomy. It is an abnormal inelastic narrowing of the anal canal due to stricture of the epithelial lining, which is replaced by fibrous connective tissue [1]. The incidence of anal stenosis after a hemorrhoidectomy can be as high as 5% [2], with 90% of the cases caused by overzealous hemorrhoidectomies [3]. Treatment, both medical and surgical, should be decided based on the severity of the stenosis [4, 5]. In patients with severe anal stenosis, a sphincterotomy and various anoplasty techniques should be done: these techniques include scar excision, a partial internal sphincterotomy, and reshaping of the area with mucosal flaps or skin or with both in various configurations [1]. Several corrective techniques for severe anal stenosis have been described in the literature [5-7]. The rotational S flap is one of those used. This manuscript reports on two cases of severe circular anal stenosis treated with this technique to prevent restenosis.

This study has been approved by the Institutional Review Board of the Faculty of Medicine, Universitas Gadjah Mada Indonesia under permit ethic approval protocol number KE/0896/08/2018. The authors attest that full and informed consent was obtained from every single patient who have undergone medical treatment in our Hospital. The informed consent form also declared that patient data or samples will be used or educational or research purposes.

Anal stenosis is a condition that causes patients to feel uncomfortable. Common symptoms are pain with defecation, constipation, obstipation, narrow stool caliber, and bleeding [8]. Strong evidence supports the diagnosis of anal stenosis based on symptoms, history of anal surgery, and local inspection using a digital rectal examination. In our patients, both had a history of hemorrhoidectomy procedures. These patients were diagnosed as having severe anal stenosis when the little finger could not be inserted into the anal canal upon digital rectal examination; the validity of using this criterion for diagnosing anal stenosis had been previously reported by Tahamtan et al. [9] and Milsom and Mazier [10].

For treating severe anal stenosis, we use a sphincterotomy and various anoplasty procedures. These procedures include scar excision, a partial internal sphincterotomy, and reshaping of the area with mucosal flaps, skin, or a combination of the two, in various configurations [1]. Several techniques, such as the C flap, the House flap, the U flap, and the rotational S flap techniques, are indicated for the treatment of severe anal stenosis [6], but one procedure is not ideal for every patient. The choice of surgery must be adjusted to the individual patient [11]. The authors selected the rotational S flap technique due to the characteristic stricture in these patients and a circumferential scar. This method can be performed bilaterally, which coincides with the work of Hudson et al. [12] and Kościński [13]; the treatment of circular anal stenosis requires a circumferential excision and the formation of 2 wide rotational flaps to cover the tissue defect.

The rotational S flap was chosen, as it has a better pedicle for preserving good vascular supply, compared to the House flap and the U flap techniques, as described by Brisinda et al. [6]; they maintain that the rotational S flap provides an adequate blood supply, avoids tension, and can be performed bilaterally if necessary for coverage of large areas with skin. Careful selection of anoplasty techniques according to the size and the shape of the stenosis and preservation of the vascular supply for advancement of the flap without excessive tension in the suture line can produce good outcomes, as already explained by Kościński [13].

Vascularity plays an important role in preventing hypoxic conditions. In contrast, poor perfusion creates hypoxic wounds, which disrupt the healing process. According to reports in the literature, hypoxia inducible factor-1, which is expressed in hypoxic conditions, will trigger the onset of fibrosis and scarring [14], as mentioned by Tandara and Mustoe [15]. The presence of impaired wound healing will impact the presence of fibrosis due to a buildup of fibroblasts with hypoxic features [15]. A good vascular supply can accelerate wound healing and prevent stricture occurrence. We chose the rotational S flap to promote this healing process.

Given severe circular anal stenosis, the author rated the bilateral rotational S flap as a simple technique compared to the House flap and the U flap approaches because both approaches must be done multiple times to reconstruct the wound after excision of the circular anal fibrosis.

In conclusion, the bilateral rotational S flap technique should be considered as a viable treatment because it can also prevent the occurrence of restenosis after treatment for circular severe anal stenosis, especially given the consideration of adequate blood supply.